KMS of Xinjiang Astronomical Observatory, CAS
| 基于Kepler 天区的盾牌座Delta Scuti 星震学研究 | |
| Alternative Title | An asteroseismological study of Delta Scuti stars in the Kepler sky region |
吕成龙
| |
| Subtype | 硕士 |
| Thesis Advisor | 艾力·伊沙木丁 |
| 2021-06-01 | |
| Degree Grantor | 中国科学院大学 |
| Place of Conferral | 北京 |
| Degree Name | 理学硕士 |
| Degree Discipline | 天体物理 |
| Keyword | 盾牌座Delta型脉动变星 Kepler太空望远镜 星震学 KIC 12602250 KIC 5197256 |
| Abstract | 盾牌座Delta型脉动变星是一类很早就被发现具有多重脉动周期的变星，该类变星具有银河系内第二丰富的脉动信息，因而，一直被认为是星震学的重要研究对象。该类变星的质量在1.5-2.5M⊙之间，主要处于中心氢燃烧阶段，部分变星中心氢刚刚耗尽离开主序，少数变星属于主序前恒星。主序前演化是恒星演化的最早期，决定着恒星一生。盾牌座Delta型脉动变星的观测研究，我们可以得到恒星不同的脉动模式。本文利用星震学对盾牌座Delta型脉动变星进行了研究。星震学是研究恒星内部结构和物理过程最有效的方法，对恒星进行星震学研究能够获得恒星内部结构和演化状态更加精确的信息，对于了解主序前及主序后阶段恒星的内部结构与演化具有十分重要的意义。KIC 12602250是由开普勒太空望远镜发现的一颗低振幅盾牌座Delta型脉动变星，该星被开普勒太空望远镜连续观测1471天，本文对其光变曲线进行了细致的分析和研究，发现该星只有径向基频脉动和第一谐频脉动两种脉动模式。这是首次发现低振幅的Delta型脉动变星具有HADS的脉动特征。通过对振幅最大的三个脉动频率进行振幅变化研究发现，除了径向脉动基频外的两个脉动频率随时间有振幅增长的趋势，分析结果表明该变化趋势可能是恒星演化的结果，产生变化的具体原因还需后续光谱观测以及星震学模型进一步的确定和深入的研究。 KIC 5197256是由开普勒太空望远镜发现的包含一颗Delta型脉动子星的双星，该星被开普勒望远镜以SC模式观测29天，LC模式观测612天。本研究工作确定了该星265个光极小时刻，使用经典O-C分析发现该星在接近两年的时间里，周期没有明显的变化，可能是双星间的物质转移很弱或观测时长不够导致的。对剔除双星轨道信号后时序光变曲线数据进行傅里叶变换，共提取出34个显著频率，分别使用直方图方法及F-T方法得到该星的最大频率间隔为1.8 d−1。通过最大频率间隔与恒星平均密度关系本文得到其中Delta Scuti的密度为0.05 g·cm−3，同时在频率25 d−1 - 34 d−1范围内发现了五个频率间隔为1.8 d−1的频率，分析结果表明该频率分裂可能是由恒星高速旋转造成的。 |
| Other Abstract | The 𝛿 Sct stars are a class of variable stars with multiple pulsation periods, and they have the second richest pulsation information in the Milky Way, thus, they have been considered as important objects for asteroseismological studies. The mass of these variable stars is between 1.5-2.5 M⊙, and they are mainly in the central hydrogen burning stage, some of them have just depleted their central hydrogen and left the main sequence, and a few of them are pre-main-sequence stars. The pre-main-sequence evolution is the earliest stage of the stellar evolution of the star. The observational study of 𝛿 Sct stars allows us to obtain the different pulsation patterns of the stars. In this paper, we investigate 𝛿 Sct stars using the asteroseismology method. The study of stellar internal structure and physical processes is the most effective method, and the study of stellar asteroseismology can obtain more accurate information on the internal structure and evolutionary state of stars, which is very important for understanding the internal structure and evolution of stars in the pre-and post-main-sequence. KIC 12602250 is a low-amplitude 𝛿 Sct star discovered by Kepler Space Telescope, which has been continuously observed by Kepler Space Telescope for 1471 days, and its light curve has been carefully analyzed and studied in this paper. This is the first time that a low-amplitude 𝛿 Sct star is found to have the pulsation characteristics for HADS. The amplitude variation of the three largest frequencies is investigated, and it is found that the two pulsation frequencies, except the radial pulsation fundamental frequency, have a tendency to increase in amplitude with time, and the analysis results indicate that the variation trend may be the result of stellar evolution, and the specific reasons for the variation need further determination and study by subsequent spectroscopic observations and asteroseismological models. KIC 5197256 is a binary star containing a 𝛿 Sct star discovered by the Kepler Space Telescope, which was observed by the Kepler telescope for 29 days in SC mode and 612 days in LC mode. The present work determines 265 optical minimal moments of the star, and using classical O-C analysis finds that the period of the star does not change significantly for close to two years, possibly due to a weak material transfer between the binary stars or insufficient observation time. The Fourier transform of the light curve after removing the binary orbital signal extracts a total of 34 significant frequencies, and the maximum frequency interval of the star is 1.8 d−1 using the histogram method and the F-T method, respectively. The relationship between the maximum frequency interval and the average density of the star is obtained, in which the density of 𝛿 Sct is 0.05 g⋅cm−3, and five frequencies with the frequency interval of 1.8 d−1 are found in the frequency range of 25 d−1 - 34 d−1, which indicates that the frequency splitting may be caused by the high-speed rotation of the star. |
| Pages | 63 |
| Language | 中文 |
| Document Type | 学位论文 |
| Identifier | http://ir.xao.ac.cn/handle/45760611-7/4742 |
| Collection | 研究生学位论文 |
| Affiliation | 中国科学院新疆天文台 |
| First Author Affilication | Xinjiang Astronomical Observatory, Chinese Academy of Sciences |
| Recommended Citation GB/T 7714 | 吕成龙. 基于Kepler 天区的盾牌座Delta Scuti 星震学研究[D]. 北京. 中国科学院大学,2021. |
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| File Name/Size | DocType | Version | Access | License | ||
| 基于Kepler 天区的盾牌座Delta（4053KB） | 学位论文 | 暂不开放 | CC BY-NC-SA | Application Full Text | ||
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